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Matching section layout vs. crab-cavity voltage

Matching section layout vs. crab-cavity voltage. Barbara Dalena A. Chancé , J. Payet R. De Maria, S. Fartoukh. Contents. introduction and motivation reduction of crab voltage new IR1/5 Matching S ection (MS) layout (except Inner Triplet (IT), see R. De M aria’s talk)

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Matching section layout vs. crab-cavity voltage

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  1. Matching section layout vs. crab-cavity voltage Barbara Dalena A. Chancé, J. Payet R. De Maria, S. Fartoukh

  2. Contents • introduction and motivation • reduction of crab voltage • new IR1/5 Matching Section (MS) layout (except Inner Triplet (IT), see R. De Maria’s talk) • properties of the new layout • injection optics • squeeze-ability • chromatics properties 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  3. INTRODUCTION 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  4. Crab cavity voltage Reduce the voltage of the crab cavity: V  1/(*)1/2 D2 CRAB Q4 Q5 Q6 Q7 • increasing the beta • functionat the CRAB • using • MS quadrupole types • MS quadrupole positions 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  5. Optimization desiderata Higher  function at crab cavity location Compatible with injection optics (at * as low as possible) pre-squeeze within and possibly beyond the chromatic limits squeezable to very low * to back-up ATS Optics used for this study is the option with the triplet gradient of 170 T/m 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  6. New matching section layout D2 CRAB Q4 Q5 Q6 Q7 Q7+ D2 CRAB Q4 Q5 Q6 Q7 22.1 m 22.1 m new 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  7. INJECTION 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  8. Injection optics • possibility to build injection • optics with * of 2.0-3.0 m • w and w/o ATS R/L phases • difficult to build injection • optics with *  4.0 m, • because the added • quadrupole Q7+ becomes • too weak * = 2.5 m 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  9. Injection apertures • aperture problem in Q6 •  can be cured by changing • the MQML in MQYL type • apertures of the additional • Q7 magnet not modeled but • should be the same as Q7, • due to same  constraints • apertures in the triplet are • scaled to 150 mm * = 2.5 m 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  10. COLLISION 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  11. Pre-squeeze optics new layout HL-LHC baseline • optimum values of beta’s at crab cavity can be found by optimizing the distance of • the outer triplet quadrupoles Q4/Q5/Q6, and optimizing the strength of the new Q7 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  12. Squeeze optics • possibility to build squeeze • optics with the ATS scheme at • * =20, 15 cm • some sextupoles run at • maximum current *= 15cm 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  13. Squeeze apertures • no major aperture problems • up to *=15 cm in the • MatchingSection magnets • Q5 aperture closer to the n1=7 • limit than the other magnets •  can be improved by • re-orienting the beam screen • apertures in the triplet are • scaled to 150 mm 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  14. Crab-cavity voltage gain possibility to reduce the crab voltage of about 30-40% 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  15. Lattice squeeze-ability • possibility to build squeeze • optics in non ATS mode • at *  13 cm • chromaticity correction • strategy not known yet * = 14 cm 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  16. apertures • no aperture problems for the • Matching Section magnets • apertures in the triplet are • scaled to 150 mm * = 14 cm 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  17. CHROMATICS PROPERTIES 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  18. Chromaticity correction • the ATS scheme gives good • chromaticity correction • in the horizontal plane * = 15 cm • the relative tune variation • (fractional part) changes from 1% • to 2% in the vertical plane 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  19. Geometric aberrations compensation Detuning with amplitude (IP1, * = 15 cm) 3Qx = 187 4Qy-Qx = 179 3Qx-6Qy = 175 3Qx+6Qy = 549 • stop band width of the 3Qx resonance is increased • new ninth order coupling resonances are excited 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  20. Conclusion & Outlook • possibility to reduce crab cavity voltageby 30-40% • possibility to gain some lattice flexibility in collision and injection •  chromatic correction needs to be tuned • work out solutions for injection optics at *  4 m • integrate the proposed solution with the new Inner Triplet 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  21. Crab cavity voltage • reduce the voltage of the crab cavity: V  1/(*)1/2 by increasing the beta functions in Q4 IT MS-ARC 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

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